This invention relates to pharmaceutically useful compounds which inhibit cyclic guanosine 3xe2x80x2,5xe2x80x2-monophosphate phosphodiesterases (cGMP PDEs). More notably, the compounds of the invention are potent inhibitors of type 5 cyclic guanosine 3xe2x80x2,5xe2x80x2-monophosphate phosphodiesterase (cGMP PDE5) and are selective over other phosphodiesterases, including PDE6. The compounds of the invention therefore have utility in a variety of therapeutic areas.
The compounds of the invention are of value for the curative or prophylactic treatment of mammalian sexual disorders. In particular, the compounds are of value in the treatment of mammalian sexual dysfunctions such as male erectile dysfunction (MED), impotence, female sexual dysfunction (FSD), clitoral dysfunction, female hypoactive sexual desire disorder, female sexual arousal disorder, female sexual pain disorder or female sexual orgasmic dysfunction (FSOD) as well as sexual dysfunction due to spinal cord injury or selective serotonin re-uptake inhibitor (SSRI) induced sexual dysfunction but, clearly, will be useful also for treating other medical conditions for which a potent and selective cGMP PDE5 inhibitor is indicated. Such conditions include premature labour, dysmenorrhoea, benign prostatic hyperplasia (BPH), bladder outlet obstruction, incontinence, stable, unstable and variant (Prinzmetal) angina, hypertension, pulmonary hypertension, chronic obstructive pulmonary disease, coronary artery disease, congestive heart failure, atherosclerosis, conditions of reduced blood vessel patency, e.g. post-percutaneous transluminal coronary angioplasty (post-PTCA), peripheral vascular disease, stroke, nitrate induced tolerance, bronchitis, allergic asthma, chronic asthma, allergic rhinitis, diseases and conditions of the eye such as glaucoma, optic neuropathy, macular degeneration, elevated intra-occular pressure, retinal or arterial occulsion and diseases characterised by disorders of gut motility, e.g. irritable bowel syndrome (IBS).
Further medical conditions for which a potent and selective cGMP PDE5 inhibitor is indicated, and for which treatment with compounds of the present invention may be useful, include pre-eclampsia, Kawasaki""s syndrome, nitrate tolerance, multiple sclerosis, diabetic nephropathy, neuropathy including autonomic and peripheral neuropathy and in particular diabetic neuropathy and symptoms thereof (e.g. gastroparesis), peripheral diabetic neuropathy, Alzheimer""s disease, acute respiratory failure, psoriasis, skin necrosis, cancer, metastasis, baldness, nutcracker oesophagus, anal fissure, haemorrhoids, hypoxic vasoconstriction, hypoxic vasoconstriction, diabetes, type 2 diabetes mellitus, the insulin resistance syndrome, insulin resistance, impaired glucose tolerance, as well as the stabilisation of blood pressure during haemodialysis.
Particularly preferred sexual disorders include MED and FSD.
According to the present invention, there is provided compounds of general formula I: 
or a pharmaceutically or veterinarily acceptable salt and/or solvate, polymorph or pro-drug thereof, wherein
Y represents C or N, with N being in at least one, but not more than two, of the positions marked by Y;
X represents CH or N;
R1, R2 and R3 where present and attached to nitrogen independently represent H, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl;
R1, R2 and R3 where present and attached to carbon independently represent H, halo, cyano, nitro, OR6, OC(O)R6, C(O)R6, C(O)OR6, NR6C(O)NR7R8, NR6(O)OR6 OC(O)NR7R8, C(O)NR9R10, NR9R10, SO2NR9R10, SO2R11, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl;
wherein when R1 and R2 are present they may optionally be connected via a Cxe2x80x94C, Cxe2x80x94N or Cxe2x80x94O bond;
wherein when R2 and R3 are present they may optionally be connected via a Cxe2x80x94C, Cxe2x80x94N or Cxe2x80x94O bond;
R4 represents H, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl;
R5 represents C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl;
wherein when R1, R2 and R3, where present, or R4 or R5 is a C1-C6 alkyl, Het, C1-C6 alkylHet, aryl and C1-C6 alkylaryl group, such C1-C6 alkyl, Het, C1-C6 alkylHet, aryl and C1-C6 alkylaryl group is optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR6, OC(O)R6, C(O)R6, C(O)OR6, NR6C(O)NR7R8, NR6C(O)OR6, OC(O)NR7R8, C(O)NR9R10, NR9R10, SO2NR9R10, SO2R11, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl which latter five substituent groups are all optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17;
R6 represents H, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl which latter five substituent groups are all optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17;
R7 and R8 independently represent H, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl which latter five substituent groups are all optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17; or
R7 and R8 together with the nitrogen atom to which they are bound can form a heterocyclic ring which is optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12. C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17;
R9 and R10 independently represent H, C(O)R6, SO2R11, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl which latter five substituent groups are all optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17; or
R9 and R10 together with the nitrogen atom to which they are bound can form a heterocyclic ring which is optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17;
R11 represents C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl which latter five substituent groups are all optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17;
R12 represents H or C1-C6 alkyl;
R13 and R14 independently represent H or C1-C6 alkyl; or
R13 and R14 together with the nitrogen atom to which they are bound can form a heterocyclic ring;
R15 and R16 independently represent H, C(O)R12, SO2R17 or C1-C6alkyl; or
R15 and R16 together with the nitrogen atom to which they are bound can form a heterocyclic ring;
R17 represents C1-C6 alkyl;
Het represents an optionally substituted four- to twelve-membered heterocyclic group, which group contains one or more heteroatoms selected from nitrogen, oxygen, sulfur and mixtures thereof and with the proviso that when R5 is Het, said Het is C-linked to the sulphur atom of the SO2 group in general formula I
which compounds are referred to together hereinafter as xe2x80x9cthe compounds of the inventionxe2x80x9d.
According to the present invention compounds of the general formula (I) R1, R2 and R3 are only present where valency allows that this can be accommodated without Y being charged.
Preferred compounds of general formula I can be represented by general formulae IA, IB, IC, ID and IE: 
Thus according to a preferred aspect of the present invention there are provided compounds of general formulae 1A, 1B, 1C, 1D and 1E wherein:
X represents CH or N;
R1, R2 and R3 where present and attached to nitrogen independently represent H, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl;
R1, R2 and R3 where present and attached to carbon independently represent H, halo, cyano, nitro, OR6, OC(O)R6, C(O)R6, C(O)OR6, NR6C(O)NR7R8, NR6C(O)OR6, OC(O)NR7R8, C(O)NR9R10, NR9R10, SO2NR9R11, SO2R11, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl;
wherein when R1 and R2 are present they may optionally be connected via a Cxe2x80x94C, Cxe2x80x94N or Cxe2x80x94O bond;
wherein when R2 and R3 are present they may optionally be connected via a Cxe2x80x94C, Cxe2x80x94N or Cxe2x80x94O bond;
R4 represents H, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl;
R5 represents C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl;
wherein when R, R2 and R3, where present, or R4 or R5 is a C1-C6 alkyl, Het, C1-C6 alkylHet, aryl and C1-C6 alkylaryl group, such C1-C6 alkyl, Het, C1-C6 alkylHet, aryl and C1-C6 alkylaryl group is optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR6, OC(O)R6, C(O)R6, C(O)OR6, NR6C(O)NR7R8, NR6C(O)OR6, OC(O)NR7R8, C(O)NR9R10, NR9R10, SO2NR9R10, SO2R11, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl which latter five substituent groups are all optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17;
R6 represents H, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl which latter five substituent groups are all optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17;
R7 and R8 independently represent H, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl which latter five substituent groups are all optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17; or
R7 and R8 together with the nitrogen atom to which they are bound can form a heterocyclic ring which is optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17;
R9 and R10 independently represent H, C(O)R6, SO2R11, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl which latter five substituent groups are all optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17; or
R9 and R10 together with the nitrogen atom to which they are bound can form a heterocyclic ring which is optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17;
R11 represents C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl which latter five substituent groups are all optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17;
R12 represents H or C1-C6 alkyl;
R13 and R14 independently represent H or C1-C6 alkyl; or
R13 and R14 together with the nitrogen atom to which they are bound can form a heterocyclic ring;
R15 and R16 independently represent H, C(O)R12, SO2R17 or C1-C6 alkyl; or
R15 and R16 together with the nitrogen atom to which they are bound can form a heterocyclic ring;
R17 represents C1-C6 alkyl;
Het represents an optionally substituted four- to twelve-membered heterocyclic group, which group contains one or more heteroatoms selected from nitrogen, oxygen, sulfur and mixtures thereof wherein when R5 is Het then said Het is C-linked to the sulphur atom of the SO2 group in general formula I and
with the proviso that R3 does not represent H in formula IE where X is CH;
with the proviso that in formula 1A or 1 D when X is N, R5 does not represent C1-C6 alkyl, optionally substituted and/or terminated with one or more substituents selected from halo, OR17, NR12R17 or NR17C(O)R17.
The term xe2x80x9carylxe2x80x9d, when used herein, represents C1-C11 aryl groups which include phenyl and naphthyl groups.
The term xe2x80x9cHetxe2x80x9d, when used herein, includes four- to twelve-membered, preferably four- to ten-membered, ring systems, which rings contain one or more heteroatoms selected from nitrogen, oxygen, sulfur and mixtures thereof, and which rings may contain one or more double bonds or be non-aromatic, partly aromatic or wholly aromatic in character. The ring systems may be monocyclic, bicyclic or fused. The term thus includes groups such as optionally substituted azetidinyl, pyrrolidinyl, imidazolyl, indolyl, furanyl, oxazolyl, isoxazolyl, oxadiazolyl, thiazolyl, thiadiazolyl, triazolyl, tetrazolyl, oxatriazolyl, thiatriazolyl, pyridazinyl, morpholinyl, pyrimidinyl, pyrazinyl, pyridinyl, quinolinyl, isoquinolinyl, piperidinyl, pyrazolyl imidazopyridinyl and piperazinyl. Substitution at Het may be at a carbon atom of the Het ring or, where appropriate, at one or more of the heteroatoms.
xe2x80x9cHetxe2x80x9d groups may also be in the form of an N-oxide.
The heterocyclic ring that R7 and R8, R9 and R10, R13 and R14 or R15 and R16 (together with the nitrogen atom to which they are bound) may represent may be any heterocyclic ring that contains at least one nitrogen atom, and which ring forms a stable structure when attached to the remainder of the molecule via the essential nitrogen atom (which, for the avoidance of doubt, is the atom to which R7 and R8, R9 and R10, R13 and R14 or R15 and R16 are attached respectively). In this respect, heterocyclic rings that R7 and R8, R9 and R10, R13 and R14 or R15 and R16 (together with the nitrogen atom to which they are bound) may represent include four- to twelve-membered, preferably four- to ten-membered, ring systems, which rings contain at least one nitrogen atom and optionally contain one or more further heteroatoms selected from nitrogen, oxygen and sulfur, and which rings may contain one or more double bonds or be non-aromatic, partly aromatic or wholly aromatic in character. The term thus includes groups such as azetidinyl, pyrrolidinyl, imidazolyl, indolyl, triazolyl, tetrazolyl, morpholinyl, piperidinyl, pyrazolyl and piperazinyl.
The term xe2x80x9cC1-C6 alkylxe2x80x9d (which includes the alkyl part of alkylHet and alkylaryl groups), when used herein, includes methyl, ethyl, propyl, butyl, pentyl and hexyl groups. Unless otherwise specified, alkyl groups may, when there is a sufficient number of carbon atoms, be linear or branched, be saturated or unsaturated or be cyclic, acyclic or part cyclic/acyclic. Preferred C1-C6 alkyl groups for use herein are C1-C3 alkyl groups. The term xe2x80x9cC1-C6 alkylenexe2x80x9d, when used herein, includes C1-C6 groups which can be bonded at two places on the group and is otherwise defined in the same way as xe2x80x9cC1-C6 alkylxe2x80x9d. The term xe2x80x9cacylxe2x80x9d includes C(O)xe2x80x94(C1-C6)alkyl.
In the terms xe2x80x9cC1-C6 alkylHetxe2x80x9d and xe2x80x9cC1-C6 alkylarylxe2x80x9d, xe2x80x9cHetxe2x80x9d and xe2x80x9carylxe2x80x9d are as defined hereinbefore. Substituted C1-C6 alkylHet and C1-C6 alkylaryl may have substituents on the ring and/or on the alkyl chain.
Halo groups with which the above-mentioned groups may be substituted or terminated include fluoro, chloro, bromo and iodo.
The pharmaceutically or veterinarily acceptable salts of the compounds of the invention which contain a basic centre are, for example, non-toxic acid addition salts formed with inorganic acids such as hydrochloric, hydrobromic, hydroiodic, sulphuric and phosphoric acid, with carboxylic acids or with organo-sulphonic acids. Examples include the HCl, HBr, HI, sulphate or bisulphate, nitrate, phosphate or hydrogen phosphate, acetate, benzoate, succinate, saccarate, fumarate, maleate, lactate, citrate, tartrate, gluconate, camsylate, methanesulphonate, ethanesulphonate, benzenesulphonate, p-toluenesulphonate and pamoate salts. Compounds of the invention can also provide pharmaceutically or veterinarily acceptable metal salts, in particular non-toxic alkali and alkaline earth metal salts, with bases. Examples include the sodium, potassium, aluminium, calcium, magnesium, zinc and diethanolamine salts. For a review on suitable pharmaceutical salts see Berge et al, J. Pharm. Sci., 1977, 66, 1-19.
The pharmaceutically acceptable solvates of the compounds of the invention include the hydrates thereof.
Also included within the scope of the compound and various salts of the invention are polymorphs thereof.
Compounds of formula I which contain one or more asymmetric carbon atoms exist in two or more stereoisomeric forms. Where a compound of formula I contains an alkenyl or alkenylene group, cis (E) and trans (Z) isomerism may also occur. The present invention includes the individual stereoisomers of the compounds of formula I and, where appropriate, the individual tautomeric forms thereof, together with mixtures thereof. Separation of diastereoisomers or cis and trans isomers may be achieved by conventional techniques, e.g. by fractional crystallisation, chromatography or H.P.L.C. of a stereoisomeric mixture of compounds of formula I or a suitable salt or derivative thereof. An individual enantiomer of a compound of formula I may also be prepared from a corresponding optically pure intermediate or by resolution, such as by H.P.L.C. of the corresponding racemate using a suitable chiral support or by fractional crystallisation of the diastereoisomeric salts formed by reaction of the corresponding racemate with a suitable optically active acid or base, as appropriate.
All stereoisomers are included within the scope of the invention.
A preferred group of compounds according to a further aspect of the invention, are compounds of formulae IA, IB, IC, ID and IE as hereinbefore defined, wherein:
X represents CH or N;
R1, R2 and R3, where present, independently represent C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl optionally substituted and/or terminated with one or more substituents selected from halo, OR6, C(O)OR6 and NR9R10;
R4 represents C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl optionally substituted and/or terminated with one or more substituents selected from halo and OR6;
R5 represents C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl (these groups are all optionally substituted and/or terminated with one or more substituents selected from halo, OR6, C(O)OR6 and NR9R10);
wherein R6, R9 and R10 are as hereinbefore defined;
with the proviso that when R5 is Het, said Het is C-linked to the sulphur atom of the SO2 group in general formula I; and
with the proviso that R3 does not represent H in formula IE when X is CH; and
with the proviso that in formula 1A or 1D when X is N, R5 does not represent C1-C6 alkyl, optionally substituted and/or terminated with one or more substituents selected from halo, OR17, NR12R17 or NR17C(O)R17.
A more preferred group of compounds according to a further aspect of the invention, are compounds of formulae IA, IB, and ID as hereinbefore defined, wherein:
X represents CH or N, and wherein X is preferably CH;
R1, R2 and R3, where present, independently represent C1-C6 alkyl, Het or C1-C6 alkylHet optionally substituted and/or terminated with one or more substituents selected from OR6, C1-C6 alkyl and NR9R10;
R4 represents C1-C6 alkyl, C1-C6 alkylHet, optionally substituted and/or terminated with OR6;
R5 represents C1-C6 alkyl optionally substituted and/or terminated with one or more substituents selected from halo, OR6, C(O)OR6 and NR9R10;
wherein R6, R9 and R10 are as hereinbefore defined
with the proviso that in formula 1A or 1D when X is N, R5 does not represent C1-C6 alkyl, optionally substituted and/or terminated with one or more substituents selected from halo, OR17, NR12R17 or NR17C(O)R17.
A more preferred group of compounds herein are compounds of general formulae IA and ID which can be represented by the general formula IG: 
wherein general formula IG represents formula IA and ID depending upon whether RG is R1 or R2 as defined hereinbefore.
Thus according to a preferred aspect the present invention provides compounds of general formula IG wherein:
X represents CH or N, and wherein X is preferably CH;
RG is R1 or R2;
R1, R2 and R3, where present, independently represent C1-C6 alkyl, Het or C1-C6 alkylHet optionally substituted and/or terminated with one or more substituents selected from OR6, C1-C6 alkyl and NR9R10;
R4 represents C1-C6 alkyl, C1-C6 alkylHet, optionally substituted and/or terminated with OR6;
R5 represents C1-C6 alkyl optionally substituted and/or terminated with one or more substituents selected from halo, OR6, C(O)OR6 and NR9R10;
wherein R6, R9 and R10 are as hereinbefore defined
with the proviso that when X is N, R5 does not represent C1-C6 alkyl, optionally substituted and/or terminated with one or more substituents selected from halo, OR17, NR12R17 or NR17C(O)R17.
A preferred group of compounds of general formula IG include those wherein:
X represents CH;
RG is R1 and represents C1-C3 alkyl or C1-C3 alkylHet wherein said C1-C3 alkyl group is optionally substituted and/or terminated with one or more substituents selected from halo, OR6, C(O)OR6 and NR9R10 and wherein said C1-C3 alkylHet group is optionally substituted and/or terminated with one or more substituents selected from halo, C1-C6 alkyl, OR6, C(O)OR6 and NR9R10;
R3 represents C1-C6 alkyl optionally substituted and/or terminated with one or more substituents selected from halo and OR6;
R4 represents C1-C6 alkyl or C1-C6 alkylHet optionally substituted and/or terminated with one or more substituents selected from halo and OR6;
R5 represents C1-C6 alkyl optionally substituted and/or terminated with one or more substituents selected from halo and OR6;
A further preferred group of compounds of general formula IG include those wherein:
X represents CH;
RG represents R1 which represents methyl, ethyl or C1-C3 alkylHet wherein said C1-C3 alkylHet group is optionally substituted and/or terminated with one or more substituents selected from halo, C1-C6 alkyl, OR6, C(O)OR6 and NR9R10 and wherein R1 is preferably C1-C3 alkylHet optionally substituted and/or terminated with one or more substituents selected from C1-C6 alkyl and OR6 and wherein said Het group is a C-linked 5 or 6 membered saturated or unsaturated heterocyclic group containing at least one nitrogen atom and optionally including oxygen or sulphur atoms and wherein said Het is more preferably a C-linked 5 or 6-membered heterocyclic group containing one or two nitrogen atoms;
R3 represents C2-C4 alkyl, and is preferably ethyl, n-propyl or iso-propyl and is most preferably ethyl;
R4 represents C2-C4 alkyl optionally substituted and/or terminated with one or more substituents selected from halo and OR6 and wherein when said is C2-C4 alkyl group is preferably propyl;
R5 represents C1-C4 alkyl and wherein R5 is preferably C1-C3 alkyl, more preferably methyl or ethyl, most preferably methyl;
wherein R6, R9 and R10 are independently selected from methyl or ethyl groups.
An alternative preferred group of compounds herein are compounds of general formulae IG wherein:
X represents CH;
RG represents R2 and is C1-C6 alkyl, Het or C1-C3 alkylHet wherein said C1-C6 alkyl, Het or C1-C3 alkylHet groups are optionally substituted and/or terminated with one or more substituents selected from halo, C1-C6 alkyl, OR6, C(O)OR6 and NR9R10 and wherein when R2 represents C1-C6 alkyl, said alkyl group may be straight chain, branched chain or part or wholly cyclic;
R3, R4 and R5 independently represent C1-C6 alkyl optionally substituted and/or terminated with one or more substituents selected from halo and OR6;
An additional alternative preferred group of compounds of general formula IG include those wherein:
X represents CH;
RG represents R2 and is C1-C5 alkyl, Het or alkylHet wherein the Het groups of said Het or alkyl Het is a C-linked Het group which is optionally substitued and/or terminated with one or more substituents selected from halo, C1-C6 alkyl, OR6, C(O)OR6 and NR9R10, wherein when RG is alkyl Het, then said alkylHet group is preferably a 5 or 6-membered saturated or unsaturated heterocyclic group containing at least one nitrogen atom and optionally including oxygen or sulphur atoms and is preferably a pyrrolidinyl or an imidazolyl group and wherein when RG is Het, then said Het group is a 4 or 5-membered heterocyclic group containing one or two nitrogen atoms and is preferably an azetidinyl group wherein the N can be optionally substituted as described hereinbefore and wherein when RG is C1-C5 alkyl said alkyl is preferably cyclopropylmethyl;
R3 represents C2-C4 alkyl, and is preferably ethyl, n-propyl or iso-propyl and is most preferably ethyl;
R4 represents C2-C4 alkyl and is preferably propyl or butyl
R5 represents C1-C4 alkyl and wherein R5 is preferably C1-C3 alkyl and is more preferably methyl or ethyl, most preferably methyl;
wherein R6, R9 and R10 are independently selected from methyl or ethyl groups.
An alternative additional groups of compounds preferred herein are compounds of general formula IG wherein:
X is CH;
when RG is R1, RG represents C1-C3 alkyl or RG represents C1-C6 alkylHet, preferably C1-C3 pyridyl or pyrazolyl and wherein when RG is R1 then RG is more preferably C1-C3 alkyl, most preferably methyl; or
when RG is R2, RG represents C1-C6 alkylHet, wherein said Het is C-linked and is preferably C1-C3 imidazolyl or pyrazolyl or RG represents Het wherein said Het is C-linked and is preferably an optionally N-substitued azetidinyl group or RG represents C1-C5 alkyl and is preferably cyclopropylmethyl or methoxyethyl and wherein when RG R1 then RG is more preferably C1-C3 imidazolyl or C1-C3 pyrazolyl or cyclopropylmethyl;
R3 is C1-C6 alkyl, preferably C1-C4 alkyl and more preferably ethyl or propyl;
R4 is C1-C6 alkyl, preferably n-butyl, t-butyl, n-propyl, ethyl and more preferably ethyl when RG is R1 and more preferably propyl or t-butyl when RG is R2;
R5 is C1-C3 alkyl and is preferably methyl.
Preferred compounds of general formulae IA, IB or ID herein include the following:
5-[2-Ethoxy-5-(methylsulfonyl)phenyl]-1-methyl-3-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
5-[2-Butoxy-5-(methylsulfonyl)phenyl]-3-ethyl-2-(2-methoxyethyl)-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
3-Ethyl-5-[2-isobutoxy-5-(methylsulfonyl)phenyl]-1-(2-pyridinylmethyl)-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
5-[2-Butoxy-5-(methylsulfonyl)phenyl]-3-ethyl-1-(2-pyridinylmethyl)-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
3-Ethyl-5-[2-isobutoxy-5-(methylsulfonyl)phenyl]-1-[(1-methyl-1H-imidazol-2-yl)methyl]-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
5-[2-Butoxy-5-(methylsulfonyl)phenyl]-3-ethyl-2-[2-(4-morpholinyl)ethyl]-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
3-Ethyl-5-[2-isobutoxy-5-(methylsulfonyl)phenyl]-2-[(1-methyl-1H-imidazol-2-yl)methyl]-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
3-Ethyl-5-[2-isobutoxy-5-(methylsulfonyl)phenyl]-2-[2-(4-morpholinyl)ethyl]-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
3-Ethyl-5-[5-(methylsulfonyl)-2-propoxyphenyl]-1-(2-pyridinylmethyl)-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
2-(Cyclopropylmethyl)-3-ethyl-5-[5-(methylsulfonyl)-2-propoxyphenyl]-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
3-Ethyl-5-[2-isobutoxy-5-(methylsulfonyl)phenyl]-1-{[(2S)-1-methylpyrrolidinyl]methyl}-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
3-Ethyl-5-[2-isobutoxy-5-(methylsulfonyl)phenyl]-2-{[(2R)-1-methylpyrrolidinyl]methyl}-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
3-Ethyl-5-[2-isobutoxy-5-(methylsulfonyl)phenyl]-2-(3-pyridazinylmethyl)-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
3-Ethyl-5-[2-isobutoxy-5-(methylsulfonyl)phenyl]-1-(3-pyridazinylmethyl)-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
3-Ethyl-5-[2-isobutoxy-5-(methylsulfonyl)phenyl]-2-(2-pyridinylmethyl)-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
3-Ethyl-1-{[(2S)-1-methylpyrrolidinyl]methyl}-5-[5-(methylsulfonyl)-2-propoxyphenyl]-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
5-[2-Butoxy-5-(methylsulfonyl)phenyl]-3-ethyl-2-(1-isopropyl-3-azetidinyl)-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
3-Ethyl-5-[2-isobutoxy-5-(methylsulfonyl)phenyl]-1-(1-isopropyl-3-azetidinyl)-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
3-Ethyl-5-[2-isobutoxy-5-(methylsulfonyl)phenyl]-2-(1-methyl-4-piperidinyl)-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
3-Ethyl-5-[2-isobutoxy-5-(methylsulfonyl)phenyl]-2-(1-isopropyl-4-piperidinyl)-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
1-[2-(Diisopropylamino)ethyl]-3-ethyl-5-[5-(methylsulfonyl)-2-propoxyphenyl]-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
2-[2-(Diisopropylamino)ethyl]-3-ethyl-5-[5-(methylsulfonyl)-2-propoxyphenyl]-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
3-Ethyl-5-[5-(ethylsulfonyl)-2-propoxyphenyl]-1-{[(2S)-1-methylpyrrolidinyl]methyl}-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one;
3-Ethyl-1-{[(2S)-1-methylpiperidinyl]methyl}-5-[5-(methylsulfonyl)-2-propoxyphenyl]-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one or
5-Allyl-2-[2-butoxy-5-(methylsulfonyl)phenyl]-7-ethylimidazo[5,1-f][1,2,4]triazin-4(3H)-one.
and pharmaceutically acceptable salts, solvates, pro-drugs or polymorphs thereof.
Also included within the scope of the invention are radiolabelled derivatives of compounds of formulae I, IA, IB, IC, ID and IE which are suitable for biological studies.
The present invention additionally provides compounds of general formula I: 
or a pharmaceutically or veterinarily acceptable salt and/or solvate, polymorph or pro-drug thereof, wherein
Y represents C or N, with N being in at least one, but not more than two, of the positions marked by Y;
X represents CH or N;
R1, R2 and R3 where present and attached to nitrogen independently represent H, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl;
R1, R2 and R3 where present and attached to carbon independently represent H, halo, cyano, nitro, OR6, OC(O)R6, C(O)R6, C(O)OR6, NR6C(O)NR7R8, NR6C(O)OR6, OC(O)NR7R8, C(O)NR9R10, NR9R10, SO2NR9R10, SO2R11, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl;
wherein when R1 and R2 are present they may optionally be connected via a Cxe2x80x94C, Cxe2x80x94N or Cxe2x80x94O bond;
wherein when R2 and R3 are present they may optionally be connected via a Cxe2x80x94C, Cxe2x80x94N or Cxe2x80x94O bond;
R4 represents H, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl;
R5 represents represent C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl;
wherein when R1, R2 and R3, where present, or R4 or R5 is a C1-C6 alkyl, Het, C1-C6 alkylHet, aryl and C1-C6 alkylaryl group, such C1-C6 alkyl, Het, C1-C6 alkylHet, aryl and C1-C6 alkylaryl group is optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR6, OC(O)R6, C(O)R6, C(O)OR6, NR6C(O)N R7R8, NR6C(O)OR6, OC(O)NR7R8, C(O)NR9R10, NR9R10, SO2NR9R10, SO2R11, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl which latter five substituent groups are all optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17;
R6 represents H, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl which latter five substituent groups are all optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17;
R7 and R8 independently represent H, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl which latter five substituent groups are all optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12 C(O)OR12, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17; or
R7 and R8 together with the nitrogen atom to which they are bound can form a heterocyclic ring which is optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17;
R9 and R10 independently represent H, C(O)R6, SO2R11, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl which latter five substituent groups are all optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR13R14, C(O)NR15 R6, NR15 R16, SO2NR15R16, SO2R17; or
R9 and R10 together with the nitrogen atom to which they are bound can form a heterocyclic ring which is optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17;
R11 represents C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl which latter five substituent groups are all optionally substituted and/or terminated with one or more substituents selected from halo, cyano, nitro, OR12, OC(O)R12, C(O)R12, C(O)OR12, NR12C(O)NR13R14, NR12C(O)OR12, OC(O)NR13R14, C(O)NR15R16, NR15R16, SO2NR15R16, SO2R17;
R12 represents H or C1-C6 alkyl;
R13 and R14 independently represent H or C1-C6 alkyl; or
R13 and R14 together with the nitrogen atom to which they are bound can form a heterocyclic ring;
R15 and R16 independently represent H, C(O)R12, SO2R17 or C1-C6 alkyl; or
R15 and R16 together with the nitrogen atom to which they are bound can form a heterocyclic ring;
R17 represents C1-C6 alkyl;
Het represents an optionally substituted four- to twelve-membered heterocyclic group, which group contains one or more heteroatoms selected from nitrogen, oxygen, sulfur and mixtures thereof.
According to a further aspect of the invention there is provided processes for the preparation of compounds of the invention, as illustrated below.
The following processes are illustrative of the general synthetic procedures which may be adopted in order to obtain the compounds of the invention:
1. Compounds of formulae IA, IC, ID and IE may be prepared by cyclisation of corresponding compounds of formulae IIA, IIC, IID and IIE, respectively: 
xe2x80x83wherein R1, R2, R3, R4, R5 and X are as defined previously for compounds of formulae IA, IC, ID and IE.
This cyclisation may be accomplished under basic, neutral or acidic conditions using known methods for pyrimidone ring formation. Preferably, the cyclisation is performed under basic conditions using an alkali metal salt of an alcohol or amine, such as sodium ethoxide, potassium tert-butoxide, cesium carbonate or potassium bis(trimethylsilyl)amide, in the presence of a suitable alcohol as solvent, for example at reflux temperature (or, if performed in a sealed vessel, at greater than reflux temperature). The skilled person will appreciate that, when an alcohol is selected as solvent, an appropriate alcohol of formula R4OH may be used if it is intended to mitigate alkoxide exchange at the 2-position of either the pyridin-3-yl or phenyl substituent. Conversely, a sterically hindered alcohol (e.g. 3-methyl-3-pentanol) may be used to avoid exchange at the 2-position of either the pyridin-3-yl or phenyl substituent. Optionally, an equivalent of an additive (e.g. R4OAc) may be added to act as a hydroxide scavenger.
Compounds of formulae IIA, IIC, IID and IIE may be prepared by reaction of corresponding compounds of formulae IIIA, IIIC, IIID and IIIE, respectively: 
wherein R1, R2 and R3 are as defined previously for compounds of formulae IIA, IIC, IID and IIE, with a compound of formula IV or a carboxylic acid derivative thereof: 
wherein R4, R5 and X are as defined previously for compounds of formulae IIA, IIC, IID and IIE.
This coupling reaction may be achieved by conventional amide bond forming techniques which are well known to those skilled in the art. For example, an acyl halide (e.g. chloride) derivative of a compound of formula IV may be reacted with a compound of formula IIIA, IIIC, IIID or IIIE in the presence of an excess of a tertiary amine, such as triethylamine or pyridine, optionally in the presence of a suitable catalyst, such as 4-dimethylaminopyridine, in a suitable solvent such as dichloromethane or THF, at a temperature of about 0xc2x0 C. to room temperature.
A variety of other amino acid coupling methodologies may be used to couple the compounds of formulae IIIA, IIIC, IIID or IIIE with the compound of formula IV. For example, the acid of formula IV or a suitable salt thereof (e.g. sodium salt) may be activated with an appropriate activating reagent, e.g. a carbodiimide, such as 1,3-dicyclohexylcarbodiimide or 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride optionally in the presence of 1-hydroxybenzotriazole hydrate and/or a catalyst such as 4-dimethylaminopyridine; a halotrisaminophosphonium salt such as bromo-tris(pyrrolidinyl)phosphonium hexafluorophosphate; a suitable pyridinium salt such as 2-chloro-1-methyl pyridinium chloride; or another suitable coupling agent such as O-(7-azabenzotriazol-1-yl)-N,N,Nxe2x80x2,Nxe2x80x2-tetramethyl-uronium hexafluorophosphate (HATU). Either type of coupling reaction may be conducted in a suitable solvent such as dichloromethane, tetrahydrofuran or N,N-dimethylformamide, optionally in the presence of a tertiary amine such as N-methylmorpholine or N-ethyldiisopropylamine (for example when either the compound of formula IIIA, IIIC, IIID or IIIE, or the activating agent is presented in the form of an acid addition salt), at from about 0xc2x0 C. to about room temperature. Preferably, from about 1 to 2 molecular equivalents of the activating reagent and from 1 to 3 molecular equivalents of any tertiary amine present may be employed.
Alternatively, the carboxylic acid function of IV may be activated using an excess of a reagent such as N,Nxe2x80x2-carbonyldiimidazole in an appropriate solvent, e.g. ethyl acetate, dichloromethane or butan-2-one, at from about room temperature to about 80xc2x0 C., followed by reaction of the intermediate imidazolide with either a compound of the formula IIIA, IIIC, IIID or IIIE at from about 20xc2x0 C. to about 90xc2x0 C.
In a further variation, a compound of formula IA, IC, ID or IE, as defined previously, may be formed in a one-pot procedure by coupling a compound of formula IIA, IIIC, IIID or IIIE with the acyl chloride or a lower alkyl ester derivative of formula IV and by cyclising the resultant intermediate compound of formula IIA, IIC, IID or IIE, using the methods as described previously. When using an acyl chloride derivative of formula IV, a suitable solvent (e.g. pyridine) may serve as both an acid scavenger and as the solvent for the in-situ coupling and cyclisation reaction.
Compounds of formula IV, where X is CH and R5 is Me, may be prepared from compounds of formula V: 
wherein R4 is as defined previously for compounds of formula IV, and Rpis a protecting group for a carboxylic acid (preferably a lower alkyl group such as methyl, ethyl or t-butyl), by using standard methods for deprotection.
Compounds of formula V may be prepared by the alkylation of compounds of formula VI: 
wherein Rp is as defined previously for compounds of formula V, by reaction with a compound of formula R4-L, wherein R4 is as defined previously for compounds of formula V, and L is a leaving group, such as halo, preferably chloro, bromo or iodo, for example at between room and reflux temperature in a suitable solvent (e.g. acetonitrile) in the presence of a suitable base (e.g. cesium carbonate).
Compounds of formula VI may be prepared from compound VII using standard conditions for protecting carboxylic acids. 
Alternatively, compounds of formula IV may be prepared from compounds of formula VIII: 
wherein R4, R5 and X are as defined previously for compounds of formula IV, by reaction with an oxidant (e.g. meta chloroperbenzoic acid (mCPBA)), for example at between 0xc2x0 C. and room temperature in a suitable solvent (e.g. dichloromethane).
Compounds of formula VII may be prepared from compounds of formula IX by first forming an intermediate diazonium salt, for example by the action of sodium nitrite in a mixture of concentrated hydrochloric acid and glacial acetic acid at from about xe2x88x9225xc2x0 C. to about 0xc2x0 C., followed by reaction with R5SSR5 and a copper salt, preferably CuBr2, for example at between 0xc2x0 C. and room temperature: 
wherein R4, R5 and X are as defined previously for compounds of formula VIII.
Compounds of formula IX may be prepared by reducing compounds of formula X: 
wherein R4 and X are as defined previously for compounds of formula IX, for example with hydrogen at 60 psi in a suitable solvent (e.g. R4OH) at between room temperature and 60xc2x0 C. in the presence of an appropriate catalyst (e.g. 10% palladium on carbon).
Alternatively, compounds of formula VIII may be prepared from compounds of formula XI: 
wherein R4, R5 and X are as defined previously for compounds of formula VII, and RP is a protecting group for a carboxylic acid (preferably a lower alkyl group such as methyl, ethyl or t-butyl), by using standard methods for deprotection.
Compounds of formula XI may be prepared from compounds of formula XII: 
wherein R4, X and RP are as defined previously for compounds of formula XI, by reaction with thiourea (1.1 equivalents) and a nickel (0) catalyst, generated in situ from bis(triethylphosphine)nickel(II) chloride (0.05 equivalents) and sodium cyanoborohydride (0.075 equivalents), in a suitable solvent (e.g. N,N-dimethylformamide) at between room temperature and 80xc2x0 C., followed by addition of R5-L (wherein R5 is as defined previously for compounds of formula XI and L is a leaving group such as halo, preferably chloro, bromo or iodo) and a suitable base (e.g. calcium oxide).
Compounds of formula XII, where X is N, may be prepared from compounds of formula XIII: 
wherein R4 and RP are as defined previously for compounds of formula XII, by reaction with N-iodosuccinimide (1 to 2 equivalents) in a 4:1 mixture of trifluoroacetic acid and trifluoroacetic anhydride at between room and reflux temperature.
Alternatively, compounds of formula IV may be prepared from compounds of formula XIV: 
wherein R4, R5 and X are as defined previously for compounds of formula IV, and RP is a protecting group for a carboxylic acid (preferably a lower alkyl group such as methyl, ethyl or t-butyl), by using standard methods for deprotection.
Compounds of formula XIV may be prepared from compounds of formula XV: 
wherein R4, X and RP are as defined previously for compounds of formula XIV, by reaction with sodium sulphite (2 equivalents) and sodium bicarbonate (2 equivalents) in water at room temperature, followed by reaction with sodium carbonate (2 equivalents) and R5-L (wherein R5 is as defined previously for compounds of formula XIV and L is a leaving group such as halo, preferably chloro, bromo or iodo) in aqueous alcohol (preferably R4OH) at between room and reflux temperature.
2. Compounds of formulae IA, IC, ID and IE, where X is CH, may alternatively be prepared by deprotecting corresponding compounds of formulae XVIA, XVIC, XVID and XVIE respectively: 
xe2x80x83wherein R1, R2, R3, R4 and R5 are as defined previously for compounds of formulae IA, IC, ID and IE, and RP is a protecting group (e.g. methyl), for example by reaction with 6M HCl at between room temperature and 70xc2x0 C.
Compounds of formulae XVIA, XVIC, XVID and XVIE may be prepared by alkylating corresponding compounds of formulae XVIIA, XVIIC, XVIID and XVIIE (the skilled person will appreciate that XVIIA and XVIID are different tautomeric forms of the same compound) respectively: 
wherein R1, R2, R3, R4, R5 and RP are as defined previously for compounds of formulae XVIA, XVIC, XVID and XVIE, by reaction with compounds of formulae R1-L, R3-L, R2-L and R3-L respectively, wherein R1, R2 and R3 are as defined previously for compounds of formulae XVIA, XVIC, XVID and XVIE, and L is a leaving group, such as halo, preferably chloro, bromo or iodo, or an alkyl or aryl sulphonate, preferably methane sulphonate or p-toluene sulphonate, for example at between room and reflux temperature in a suitable solvent (e.g. N,N-dimethylformamide) in the presence of a suitable base (e.g. potassium carbonate).
Compounds of formulae XVIIA, XVIIC, XVIID and XVIIE may be prepared by reacting corresponding compounds of formulae XVIIIA, XVIIIC, XVIIID and XVIIIE (the skilled person will appreciate that XVIIIA and XVIIID are different tautomeric forms of the same compound) respectively: 
wherein R1, R2, R3, R4 and R5 are as defined previously for compounds of formulae XVIIA, XVIIC, XVIID and XVIIE, with RP-OH, wherein RP is as defined previously for compounds of formulae XVIIA, XVIIC, XVIID and XVIIE, for example at between room and reflux temperature in the presence of a suitable base (e.g. potassium tert-butoxide).
Compounds of formulae XVIIIA, XVIIIC, XVIIID and XVIIIE may be prepared by reacting corresponding compounds of formulae XIXA, XIXC, XIXD and XIXE (the skilled person will appreciate that XIXA and XIXD are different tautomeric forms of the same compound) respectively: 
wherein R1, R R3, R4 and R5 are as defined previously for compounds of formulae XVIIIA, XVIIIC, XVIIID and XVIIIE, with a chlorinating agent (e.g. POCl3) at between room and reflux temperature, optionally in a suitable solvent and optionally in the presence of 1 to 2 equivalents of an additive (e.g. N,N-dimethylformamide or N,N-dimethylaniline). The skilled person will recognise that although the above structures have been given discreet formulae descriptors (XIXA, XIXC, XIXD and XIXE) for clarity, they are in fact a subset of formulae IA, IC, ID and IE wherein R1, R3, R2 and R3 are hydrogen respectively.
Compounds of formulae XIXA, XIXC, XIXD and XIXE may be prepared by cyclisation of corresponding compounds of formulae XXA, XXC, XXD and XXE (the skilled person will appreciate that XXA and XXD are different tautomeric forms of the same compound) respectively: 
wherein R1, R2, R3, R4 and R5 are as defined previously for compounds of formulae XIXA, XIXC, XIXD and XIXE, using the same conditions described for the preparation of IA, IC, ID and IE in process 1. The skilled person will recognise that although the above structures have been given discreet formulae descriptors (XXA, XXC, XXD and XXE) for clarity, they are in fact a subset of formulae IIA, IIC, IID and IIE wherein R1, R3, R2 and R3 are hydrogen respectively.
Compounds of formulae XXA, XXC, XXD and XXE may be prepared by reaction of corresponding compounds of formulae XXIA, XXIC, XXID and XXIE respectively: 
wherein R1, R2 and R3 are as defined previously for compounds of formulae XXA, XXC, XXD and XXE, with a compound of formula IV or a carboxylic acid derivative thereof, using the same conditions described for the preparation of IIA, IIC, IID and IIE in process 1. The skilled person will recognise that although the above structures have been given discreet formulae descriptors (XXIA, XXIC, XXID and XXIE) for clarity, they are in fact a subset of formulae IIIA, IIIC, IIID and IIIE wherein R1, R3, R2 and R3 are hydrogen respectively.
3. Compounds of formulae IIA, IIC, IID and IIE, in which R1, R2 and R3, when attached to nitrogen, do not represent hydrogen, may alternatively be prepared by reacting corresponding compounds of formulae XXA, XXC, XXD and XXE (the skilled person will appreciate that XXA and XXD are different tautomeric forms of the same compound), with compounds of formulae R1-L, R3-L, R2-L and R3-L respectively, wherein R1, R2 and R3 are as defined previously for compounds of formulae IIA, IIC, IID and IIE, and L is a leaving group, such as halo, preferably chloro, bromo or iodo, or an alkyl or aryl sulphonate, preferably methane sulphonate or p-toluene sulphonate, for example at between room and reflux temperature in a suitable solvent (e.g. N,N-dimethylformamide) in the presence of a suitable base (e.g. cesium carbonate).
4. Compounds of formulae IA, IC, ID and IE, in which R1, R2 and R3, when attached to nitrogen, do not represent hydrogen, may alternatively be prepared by reacting corresponding compounds of formulae XIXA, XIXC, XIXD and XIXE (the skilled person will appreciate that XIXA and XIXD are different tautomeric forms of the same compound), with compounds of formulae R1-L, R3-L, R2-L and R3-L respectively, wherein R1, R2 and R3 are as defined previously for compounds of formulae IA, IC, ID and IE, and L is a leaving group, such as halo, preferably chloro, bromo or iodo, or an alkyl or aryl sulphonate, preferably methane sulphonate or p-toluene sulphonate, for example at between room and reflux temperature in a suitable solvent (e.g. N,N-dimethylformamide) in the presence of a suitable base (e.g. cesium carbonate).
5. Compounds of formulae IA, IC, ID and IE, in which R1, R2 and R3, when attached to carbon, represent either cyano, C(O)R6, C(O)OR6, C(O)NR9R10, C1-C6 alkyl, Het, C1-C6 alkylHet, aryl or C1-C6 alkylaryl (which latter five groups are all optionally substituted and/or terminated as detailed in the definition of R1, R2 and R3) may alternatively be prepared by reacting corresponding compounds of formulae XXIIA, XXIIC, XXIID and XXIIE respectively: 
xe2x80x83wherein X, R4, R5, R6, R9 and R10 are as defined previously for compounds of formulae IA, IC, ID and IE, and Hal represents Cl, Br or I (preferably Br or I), with R3-FG, R1-FG, R3-FG and R2-FG respectively, wherein R1, R2 and R3 are as defined previously for compounds of formulae IA, IC, ID and IE, and FG represents the appropriate functional group (obvious to those skilled in the art) required to utilise the following coupling conditions:
(a) so-called xe2x80x9cSuzukixe2x80x9d conditions (e.g. 1.2 equivalents of a boronic acid, 2 equivalents of K2CO3 and 0.1 equivalents of Pd(PPh3)4, at reflux temperature in a 4:1 mixture of dioxane and water);
(b) so-called xe2x80x9cStillexe2x80x9d conditions (e.g. 1.5 equivalents of a stannane, 10 equivalents of LiCl, 0.15 equivalents of Cul, and 0.1 equivalents of Pd(PPh3)4, at reflux temperature in dioxane);
(c) so-called xe2x80x9cHeckxe2x80x9d conditions (e.g. 2 equivalents of an alkene [such as butyl vinyl ether to prepare C(O)R8 containing compounds], 1.7 equivalents of Et3N and catalytic amounts of Pd(OAc)2 and P(o-tol)3, in MeCN at between room and reflux temperature);
(d) so-called xe2x80x9cSonogashiraxe2x80x9d conditions (e.g. 1.5 to 5 equivalents of a terminal alkyne and 0.03 equivalents of Pd(PPh3)2Cl2/Cul, in Et3N and MeCN at between room temperature and 60xc2x0 C. [alternatively followed by hydrolysis conditions (e.g. 0.3 equivalents HgSO4, H2SO4 in acetone at reflux temperature) to prepare C(O)R8 containing compounds]).
(e) Carbonylation conditions (e.g. palladium(II) acetate combined with 1,2-bis(diphenylphosphino)-propane (DPPP) under an atmosphere of carbon monoxide (e.g. at a pressure of around 70 psi) in the presence of an excess of a nucleophile (e.g. alcohol or amine), an excess of a tertiary amine base (e.g. Et3N), and optionally in the presence of a suitable solvent (e.g. dimethylsulfoxide).
The skilled person will recognise that although the above structures have been given discreet formulae descriptors (XXIIA, XXIIC, XXIID and XXIIE) for clarity, they are in fact a subset of formulae IA, IC, ID and IE wherein R3, R1, R3 and R2 are Hal respectively.
Compounds of formulae XXIIA, XXIIC, XXIID and XXIIE may be prepared by reaction of corresponding compounds of formulae XXIIIA, XXIIIC, XXIIID and XXIIIE respectively: 
wherein X, R1, R2, R3, R4 and R5 are as defined previously for compounds of formulae XXIIA, XXIIC, XXIID and XXIIE, with the appropriate halogen (e.g. bromination can be achieved by reacting with 1.5 to 2.0 equivalents of bromine and 1.5 to 2.0 equivalents of sodium acetate in acetic acid at between room and reflux temperature). The skilled person will recognise that although the above structures have been given discreet formulae descriptors (XXIIIA, XXIIIC, XXIIID and XXIIIE) for clarity, they are in fact a subset of formulae IA, IC, ID and IE wherein R3, R1, R3 and R2 are H respectively.
Compounds of formulae XXIIIA, XXIIIC, XXIIID and XXIIIE may be prepared by analogous conditions to those described for the preparation of corresponding compounds of formulae IA, IC, ID and IE in process 1.
6. Compounds of formula XIXE may alternatively be prepared by reaction of a compound of formula XXIVE: 
xe2x80x83wherein R4 and R5 are as defined previously for compounds of formula XIXE, with a compound of formula XXVE:
R2xe2x80x94CHOxe2x80x83xe2x80x83XXVE 
xe2x80x83wherein R2 is as defined previously for compounds of formula XIXE, for example at between room and reflux temperature, optionally in the presence of a suitable mild oxidant (e.g. sodium metabisulfite), and optionally in an appropriate organic solvent (e.g. N,N-dimethylacetamide).
Compounds of formula XIXE may alternatively be prepared by reaction of compounds of formula XXIVE, as hereinbefore defined, with a compound of formula XXVIE:
R2xe2x80x94C(O)OHxe2x80x83xe2x80x83XXVIE 
wherein R2 is as defined previously for compounds of formula XIXE, or a suitable carboxylic acid derivative thereof (e.g. an acid halide or an ortho ester), for example at between room and reflux temperature, optionally in the presence of a suitable solvent (e.g. N,N-dimethyl formamide) and/or an appropriate base.
7. Compounds of formula IB may be prepared by cyclisation of compounds of formula XXVIIB: 
xe2x80x83wherein R1, R3, R4, R5 and X are as defined previously for compounds of formula IB, for example under conditions known to those skilled in the art. Such conditions include reaction, at between room and reflux temperature, in the presence of a suitable (Lewis acidic) dehydrating agent (e.g. phosphorous oxychloride) and an appropriate solvent (e.g. 1,2-dichloroethane), or as otherwise described in the art.
Compounds of formula XXVIIB may be prepared by the reaction of compounds of formula XXVIIIB: 
wherein R17 represents C1-C6 alkyl, and R1 and R3 are as defined previously for compounds of formula XXVIIB, with compounds of formula XXIXB: 
or a suitable acid addition salt thereof (e.g. an hydrogen chloride salt), wherein R4, R5 and X are as defined previously for compounds of formula XXVIIB, for example under conditions known to those skilled in the art. Such conditions include, for example, reaction at between room and reflux temperature in a suitable solvent (e.g. ethanol, ether, 1,4-dioxane or N,N-dimethylformamide).
Compounds of formula XXVIIIB may be prepared via standard techniques, for example by decarboxylation of compounds of formula XXXB: 
wherein R1, R3 and R17 are as defined previously for compounds of formula XXVIIIB, for example under conditions known to those skilled in the art. Such conditions include, for example, reaction at elevated temperature (e.g. reflux temperature) in the presence of a suitable solvent (e.g. methanol or ethanol) and optionally in the presence of a suitable base (e.g. sodium hydrogencarbonate).
Compounds of formula XXXB may be prepared by reaction of compounds of formula XXXIB: 
wherein R1 and R3 are as defined previously for compounds of formula XXXB, with a compound of formula XXXIIB: 
wherein R17 is as defined previously for compounds of formula XXXB and L is as hereinbefore defined, for example under conditions known to those skilled in the art. Such conditions include reaction, at between room and reflux temperature, in the presence of a suitable organic solvent (e.g. THF or ether), an appropriate base (e.g. pyridine, sodium hydride, potassium tert-butoxide, lithium diisopropyl-amide, piperidine or triethylamine) optionally in the presence of a suitable catalyst (e.g. 4-(dimethylamino)pyridine), and optionally with the prior conversion of XXXIB into a 1,3-oxazol-5(4H)-one with excess XXXIIB (Dakin-West reaction).
Compounds of formula XXVIIIB may alternatively be prepared by reaction of a corresponding compound of formula XXXIIIB: 
wherein R1, R3 and R17 are as defined previously for compounds of formula XXVIIIB, with ozone in a stream of oxygen, followed by reduction of the resulting ozonide, for example, for both steps, under conditions known to those skilled in the art. Conditions for the ozonation include, for example, reaction at sub-ambient temperature (e.g. xe2x88x9270xc2x0 C.) in the presence of a suitable solvent (e.g. dichloromethane). Conditions for reduction of the intermediate ozonide include, for example, reaction at sub-ambient temperature (e.g. xe2x88x9270xc2x0 C.) with a suitable reducing agent (e.g. dimethyl sulfide), followed by treatment (at the same temperature) with an appropriate base (e.g. pyridine).
Compounds of formula XXXIIIB may be prepared by reaction of a corresponding compound of formula XXXIVB: 
wherein L2 represents a suitable leaving group (e.g. xe2x80x94N(CH3)OCH3 or halo) and R1 and R3 are as defined for compounds of formula XXXIIIB, with a compound of formula XXXVB: 
wherein M represents H or a suitable metal-containing moiety (e.g. Na, Li, Mg(II) halide, or a cuprate) and R17 is as defined previously for compounds of formula XXXIIIB, for example under conditions known to those skilled in the art. Such conditions include, for example, reaction of a compound of formula XXXIVB at between xe2x88x9280xc2x0 C. and room temperature in the presence of a suitable solvent (e.g. THF) with a mixture formed by reacting, at sub-ambient temperature (e.g. xe2x88x9278xc2x0 C.), a compound of formula XXXVB in which M represents H (e.g. ethyl vinyl ether), a suitable organolithium reagent (e.g. tert-butyllithium), an appropriate solvent (e.g. THF) and, optionally, a source of a suitable metal salt (e.g. MgBr2 diethyl etherate).
Compounds of formula XXXIVB may be prepared from corresponding compounds of formula XXXIB, as hereinbefore defined, under conditions known to those skilled in the art.
Compounds of formula XXVIIIB may alternatively be prepared by reaction of corresponding compounds of formula XXXVIB: 
wherein R1, R3 and R17 are as previously defined for compounds of formula XXVIIIB, with an oxidising agent (e.g. Dess-Martin periodinane) at between xe2x88x9278xc2x0 C. and reflux temperature in a suitable solvent (e.g. DCM).
Compounds of formula XXXVIB may be prepared by the reaction of compounds of formula XXXVIIB: 
wherein R1 and R3 are as previously defined for compounds of formula XXXVIB, with HCl(g) in R17OH, wherein R17 is as previously defined for compounds of formula XXXVIB, at between xe2x88x9210xc2x0 C. and 20xc2x0 C., followed by reaction with aqueous base (e.g. 10% Na2CO3 soln.) at between 20xc2x0 C. and reflux temperature.
Compounds of formula XXXVIIB may be prepared by the reaction of compounds of formula XXXVIIIB: 
wherein R1 and R3 are as previously defined for compounds of formula XXXVIIB, with a source of cyanide (e.g. acetone cyanohydrin) in a suitable solvent (e.g. DCM), optionally in the presence of a base (e.g. Et3N), at between 0xc2x0 C. and reflux temperature.
Compounds of formula XXXVIIIB may be prepared by the reaction of compounds of formula XXXIXB: 
wherein R1 and R3 are as previously defined for compounds of formula XXXVIIIB, with a source of hydride (e.g. LiAlH4) in a suitable solvent (e.g. THF) at between xe2x88x9278xc2x0 C. and 20xc2x0 C.
Compounds of formula XXXIXB may be prepared from compounds of formula XXXIB using conditions known to those skilled in the art.
Compounds of formula XXIXB may be prepared via standard techniques, for example by a reaction of a corresponding compound of formula XXXXB: 
or an acid addition salt thereof (e.g. a hydrogen chloride salt), wherein R4, R5 and X are as defined previously for compounds of formula XXIXB, with hydrazine, for example under conditions known to those skilled in the art. Such conditions include, for example, reaction at between xe2x88x9210xc2x0 C. and room temperature in the presence of a suitable solvent (e.g. a lower alkyl (e.g. C1-3) alcohol), or as otherwise described in the prior art.
Compounds of formula XXXXB may be prepared from compounds of formula XXXXIB, which in turn can be prepared from compounds of formula XXXXIIB, which in turn can be prepared from compounds of formula IV or a carboxylic acid derivative thereof, wherein R4 and R5 and X are as defined previously for compounds of formula XXXXB, under conditions known to those skilled in the art. 
Compounds of formula XXIXB may alternatively be prepared by the reaction of compounds of formula XXXXIIIB: 
wherein R4 and R5 are as defined previously for compounds of formula XXIXB, with hydrazine in a suitable solvent (e.g. THF) at between 20xc2x0 C. and reflux temperature.
Compounds of formula XXXXIIIB may be prepared by the reaction of compounds of formula XXXXIVB: 
wherein R4 and R5 are as defined previously for compounds of formula XXXXIIIB, with a methylating agent (e.g. iodomethane) in a suitable solvent (e.g. acetone) at between 20xc2x0 C. and reflux temperature.
Compounds of formula XXXXIVB may be prepared by the reaction of compounds of formula XXXXIIB with Lawesson""s reagent in a suitable solvent (e.g. toluene) at between 20xc2x0 C. and reflux temperature.
Compounds of formulae IIIA, IIIC, IIID, IIIE, VII, X, XII (where X represents CH), XII, XV, XXIA, XXIC, XXID, XXIE, XXIVE, XXVE, XXVIE, XXXIB, XXXIIB and XXXVB and derivatives thereof, when not commercially available or not subsequently described, may be obtained either by analogy with the processes described hereinbefore, or by conventional synthetic procedures, in accordance with standard techniques, from readily available starting materials using appropriate reagents and reaction conditions. For example, compounds of formula XXIVE may be prepared by, or by analogy with, methods described in U.S. Pat. No. 4,039,544.
Substituents on the aryl and Het groups in the above-mentioned compounds may be introduced, and interconverted, using techniques which are known to those skilled in the art.
Further standard substituent or functional group interconversions and transformations that may be performed on compounds of formulae I, IA, IB, IC, ID, IE and their precursors include procedures described hereinafter. In this respect:
(i) alkoxycarbonyl may be hydrolysed to carboxy under acidic or basic conditions;
(ii) amino may be alkylated (either by reaction with an alkylating agent or by reductive alkylation) to give alkylamino or dialkylamino;
(iii) amino may be acylated to give acylamino or sulfonated to give sulfonylamino.
In addition, certain acyclic groups may be converted to certain heterocyclic groups using reagents and conditions known to those skilled in the art, for example as described in Comprehensive Heterocyclic Chemistry II, edited by A R Katritsky, C W Rees and EFV Scriven, 1st Edition, Elsevier Science Ltd., Volumes 1-11 (1996).
The compounds of the invention may be isolated from their reaction mixtures using conventional techniques.
It will be appreciated by those skilled in the art that, in the course of carrying out the above processes described above, the functional groups of intermediate compounds may need to be protected by protecting groups.
Functional groups which it is desirable to protect include hydroxy, amino and carboxylic acid. Suitable protecting groups for hydroxy include trialkylsilyl and diarylalkylsilyl groups (e.g. tert-butyldimethylsilyl, tert-butyldiphenylsilyl or trimethylsilyl), alkyl (e.g. methyl or methoxyethyl) and tetrahydropyranyl. Suitable protecting groups for amino include tert-butyloxycarbonyl, 9-fluorenylmethoxycarbonyl or benzyloxycarbonyl. Suitable protecting groups for carboxylic acid include C1-6 alkyl or benzyl esters.
The protection and deprotection of functional groups may take place before or after any of the reaction steps described hereinbefore.
Protecting groups may be removed in accordance with techniques which are known to those skilled in the art.
The use of protecting groups is fully described in xe2x80x9cProtective Groups in Organic Chemistryxe2x80x9d, edited by J W F McOmie, Plenum Press (1973), xe2x80x9cProtective Groups in Organic Synthesisxe2x80x9d, 2nd edition, T W Greene and P G M Wutz, Wiley-Interscience (1991) and xe2x80x9cProtecting Groupsxe2x80x9d by Philip J. Kocienski, Thieme, 1994.
Persons skilled in the art will also appreciate that, in order to obtain compounds of formulae I, IA, IB, IC, ID and IE, in an alternative, and, on some occasions, more convenient, manner, the individual process steps mentioned hereinbefore may be performed in a different order, and/or the individual reactions may be performed at a different stage in the overall route (i.e. substituents may be added to and/or chemical transformations performed upon, different intermediates to those mentioned hereinbefore in conjunction with a particular reaction). This will depend inter alia on factors such as the nature of other functional groups present in a particular substrate, the availability of key intermediates and the protecting group strategy (if any) to be adopted. Clearly, the type of chemistry involved will influence the choice of reagent that is used in the said synthetic steps, the need, and type, of protecting groups that are employed, and the sequence for accomplishing the synthesis.
Pharmaceutically acceptable acid addition salts of the compounds of formulae I, IA, IB, IC, ID and IE which contain a basic centre may be prepared in a conventional manner. For example, a solution of the free base may be treated with the appropriate acid, either neat or in a suitable solvent, and the resulting salt may then be isolated either by filtration of by evaporation under vacuum of the reaction solvent. Pharmaceutically acceptable base addition salts can be obtained in an analogous manner by treating a solution of a compound of formulae I, IA, IB, IC, ID and IE with the appropriate base. Both types of salt may be formed or interconverted using ion-exchange resin techniques.
The present invention also includes all suitable isotopic variations of a compound of formulae I, IA, IB, IC, ID or IE or a pharmaceutically acceptable salt thereof. An isotopic variation of a compound of formulae 1, IA, IB, IC, ID or IE, or a pharmaceutically acceptable salt thereof is defined as one in which at least one atom is replaced by an atom having the same atomic number but an atomic mass different from the atomic mass usually found in nature. Examples of isotopes that can be incorporated into compounds of formulae I, IA, IB, IC, ID or IE, and pharmaceutically acceptable salts thereof include isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorus, sulphur, fluorine and chlorine such as 2H, 3H, 13C, 14C, 15N, 170, 180, 31p, 32p, 35S, 18F and 36Cl, respectively. Certain isotopic variations of the compounds of formulae I, IA, IB, IC, ID or IE, and pharmaceutically acceptable salts thereof, for example, those in which a radioactive isotope such as 3H or 14C is incorporated, are useful in drug and/or substrate tissue distribution studies. Tritiated, i.e., 3H, and carbon-14, i.e., 14C, isotopes are particularly preferred for their ease of preparation and detectability. Further, substitution with isotopes such as deuterium, i.e., H, may afford certain therapeutic advantages resulting from greater metabolic stability, for example, increased in vivo half-life or reduced dosage requirements and hence may be preferred in some circumstances. Isotopic variations of the compounds of formulae I, IA, IB, IC, ID or IE, and pharmaceutically acceptable salts thereof of this invention can generally be prepared by conventional procedures such as by the illustrative methods or by the preparations described in the Examples and Preparations hereafter using appropriate isotopic variations of suitable reagents.
It will be appreciated by those skilled in the art that certain protected derivatives of compounds of formulae I, IA, IB, IC, ID and IE, which may be made prior to a final deprotection stage, may not possess pharmacological activity as such, but may, in certain instances, be administered orally or parenterally and thereafter metabolised in the body to form compounds of the invention which are pharmacologically active. Such derivatives may therefore be described as xe2x80x9cprodrugsxe2x80x9d. Further, certain compounds of formulae I, IA, IB, IC, ID and IE may act as prodrugs of other compounds of formulae I, IA, IB, IC, ID and IE respectively.
All protected derivatives, and prodrugs, of compounds of formulae I, IA, IB, IC, ID and IE are included within the scope of the invention.
The present invention additionally comprises the combination of a cGMP PDE5 inhibitor compound of the general formulae I, IA, IB, IC, ID or IE, wherein said combination can be administered by sequential, simultaneous or joint administration of a compound of the general formulae I, IA, IB, IC, ID or IE, with:
(1) one or more naturally occurring or synthetic prostaglandins or esters thereof. Suitable prostaglandins for use herein include compounds such as alprostadil, prostaglandin E1, prostaglandin E0, 13, 14-dihydroprostaglandin E1, prostaglandin E2, eprostinol, natural synthetic and semi-synthetic prostaglandins and derivatives thereof including those described in U.S. Pat. No. 6,037,346 issued on Mar. 14, 2000 and incorporated herein by reference, PGE0, PGE1, PGA1, PGB1, PGF1 xcex1, 19-hydroxy PGA1, 19-hydroxy-PGB1, PGE2, PGB2, 19-hydroxy-PGA2, 19-hydroxy-PGB2, PGE3xcex1, carboprost tromethamine dinoprost, tromethamine, dinoprostone, lipo prost, gemeprost, metenoprost, sulprostune, tiaprost and moxisylate; and/or
(2) one or more xcex1-adrenergic receptor antagonist compounds also known as xcex1-adrenoceptors or xcex1-receptors or xcex1 blockers. Suitable compounds for use herein include: the xcex1-adrenergic receptors as described in PCT application WO99/30697 published on Jun. 14, 1998, the disclosures of which relating to a-adrenergic receptors are incorporated herein by reference and include, selective xcex11-adrenoceptors or xcex12-adrenoceptors and non-selective adrenoceptors, suitable xcex11-adrenoceptors include: phentolamine, phentolamine mesylate, trazodone, alfuzosin, indoramin, naftopidil, tamsulosin, dapiprazole, phenoxybenzamine, idazoxan, efaraxan, yohimbine, rauwolfa alkaloids, Recordati 15/2739, SNAP 1069, SNAP 5089, RS17053, SL 89.0591, doxazosin, terazosin, abanoquil and prazosin; xcex12-blockers from U.S. Pat. No. 6,037,346 [Mar. 14, 2000] dibenarnine, tolazoline, trimazosin and dibenarnine; xcex1-adrenergic receptors as described in U.S. Pat. Nos. 4,188,390; 4,026,894; 3,511,836; 4,315,007; 3,527,761; 3,997,666; 2,503,059; 4,703,063; 3,381,009; 4,252,721 and 2,599,000 each of which is incorporated herein by reference; xcex12-Adrenoceptors include: clonidine, papaverine, papaverine hydrochloride, optionally in the presence of a cariotonic agent such as pirxamine; and/or
(3) one or more NO-donor (NO-agonist) compounds. Suitable NO-donor compounds for use herein include organic nitrates, such as mono- di or tri-nitrates or organic nitrate esters including glyceryl brinitrate (also known as nitroglycerin), isosorbide 5-mononitrate, isosorbide dinitrate, pentaerythritol tetranitrate, erythrityl tetranitrate, sodium nitroprusside (SNP), 3-morpholinosydnonimine molsidomine, S-nitroso- N-acetyl penicilliamine (SNAP) S-nitroso-N-glutathione (SNO-GLU), N-hydroxy-L-arginine, amylnitrate, linsidomine, linsidomine chlorohydrate, (SIN-1) S-nitroso-N-cysteine, diazenium diolates,(NONOates), 1,5-pentanedinitrate, L-arginene, ginseng, zizphi fructus, molsidomine, Re-2047, nitrosylated maxisylyte derivatives such as NMI-678-11 and NMI-937 as described in published PCT application WO 0012075; and/or
(4) one or more potassium channel openers. Suitable potassium channel openers for use herein include nicorandil, cromokalim, levcromakalim, lemakalim, pinacidil, cliazoxide, minoxidil, charybdotoxin, glyburide, 4-amini pyridine, BaCl2; and/or
(5) one or more dopaminergic agents, preferably apomorphine or a selective D2, D3 or D2/D3 agonist such as pramipexol and ropirinol (as claimed in WO 0023056), L-Dopa or carbi dopa, PNU 95666 (as claimed in WO 0040226); and/or
(6) one or more vasodilator agents. Suitable vasodilator agents for use herein include nimodepine, pinacidil, cyclandelate, isoxsuprine, chloroprumazine, halo peridol, Rec 15/2739, trazodone; and/or
(7) one or more thromboxane A2 agonists; and/or
(8) one or more ergot alkoloids; Suitable ergot alkaloids are described in U.S. Pat. No. 6,037,346 issued on Mar. 14, 2000 and include acetergamine, brazergoline, bromerguride, cianergoline, delorgotrile, disulergine, ergonovine maleate, ergotamine tartrate, etisulergine, lergotrile, lysergide, mesulergine, metergoline, metergotamine, nicergoline, pergolide, propisergide, proterguride, terguride; and/or
(9) one or more compounds which modulate the action of atrial natruretic factor (also known as atrial naturetic peptide), B and C type naturetic factors such as inhibitors or neutral endopeptidase; and/or
(10) one or more compounds which inhibit angiotensin-converting enzyme such as enapril, and one or more combined inhibitors of angiotensin-converting enzyme and neutral endopeptidase such as omapatrilat; and/or
(11) one or more angiotensin receptor antagonists such as losartan; and/or
(12) one or more substrates for NO-synthase, such as L-arginine; and/or
(13) one or more calcium channel blockers such as amlodipine; and/or
(14) one or more antagonists of endothelin receptors and inhibitors or endothelin-converting enzyme; and/or
(15) one or more cholesterol lowering agents such as statins (e.g. atorvastatin/Lipitorxe2x80x94trade mark) and fibrates; and/or
(16) one or more antiplatelet and antithrombotic agents, e.g. tPA, uPA, warfarin, hirudin and other thrombin inhibitors, heparin, thromboplastin activating factor inhibitors; and/or
(17) one or more insulin sensitising agents such as rezulin and hypoglycaemic agents such as glipizide; and/or
(18) one or more COX 2 inhibitors; and/or
(19) pregabalene; and/or
(20) gabapentene; and/or
(21) one or more acetylcholinesterase inhibitors such as donezipil; and/or
(22) one or more steroidal anti-inflammatory agents; and/or
(23) one or more estrogen agonists and/or estrogen antagonists, preferably raloxifene or lasofoxifene, (xe2x88x92)-cis-6-phenyl-5-[4-(2-pyrrolidin-1-yl-ethoxy)-phenyl]-5,6,7,8-tetrahydronaphthalene-2-ol and pharmaceutically acceptable salts thereof (compound A below) the preparation of which is detailed in WO 96/21656. 
(24) one or more one or more of a further PDE inhibitor, more particularly a PDE 2, 4, 7 or 8 inhibitor, preferably PDE2 inhibitor, said inhibitors preferably having an IC50 against the respective enzyme of less than 100 nM: and/or
(25) one or more of an NPY (neuropeptide Y) inhibitor, more particularly NPY1 or NPY5 inhibitor, preferably NPY1 inhibitor, preferably said NPY inhibitors (including NPY Y1 and NPY Y5) having an IC50 of less than 100 nM, more preferably less than 50 nM, suitable NPY and in particular NPY1 inhibitor compounds are described in EP-A-1097718; and/or
(26) one or more of vasoactive intestinal peptide (VIP), VIP mimetic, more particularly mediated by one or more of the VIP receptor subtypes VPAC1, VPAC or PACAP (pituitary adenylate cyclase activating peptide), one or more of a VIP receptor agonist or a VIP analogue (eg Ro-125-1553) or a VIP fragment, one or more of a xcex1-adrenoceptor antagonist with VIP combination (eg Invicorp, Aviptadil); and/or
(27) one or more of a melanocortin receptor agonist or modulator or melanocortin ehancer, such as melanotan II, PT-14, PT-141 or compounds claimed in WO-09964002, WO-00074679, WO-09955679, WO-00105401, WO-00058361, WO-00114879, WO-00113112, WO-09954358; and/or
(28) one or more of a serotonin receptor agonist, antagonist or modulator, more particularly agonists, antagonists or modulators for 5HT1A (including VML 670), 5HT2A, 5HT2C, 5HT3 and/or 5HT6 receptors, including those described in WO-09902159, WO-00002550 and/or WO-00028993; and/or
(29) one or more of a modulator of transporters for noradrenaline, dopamine and/or serotonin, such as bupropion, GW-320659; and/or
(30) one or more of a purinergic receptor agonist and/or modulator; and/or
(31) one or more of a neurokinin (NK) receptor antagonist, including those described in WO-09964008; and/or
(32) one or more of an opioid receptor agonist, antagonist or modulator, preferably agonists for the ORL-1 receptor; and/or
(33) one or more of an agonist or modulator for oxytocin/vasopressin receptors, preferably a selective oxytocin agonist or modulator; and/or
(34) one or more modulators of cannabinoid receptors; and/or
(35) one or more of an NEP inhibitor, preferably wherein said NEP is EC 3.4.24.11 and more preferably wherein said NEP inhibitor is a selective inhibitor for EC 3.4.24.11, more preferably a selective NEP inhibitor is a selective inhibitor for EC 3.4.24.11, which has an IC50 of less than 100 nM (e.g. ompatrilat, sampatrilat) suitable NEP inhibitor compounds are described in EP-A-1097719; and/or
(36) one or more compounds which inhibit angiotensin-converting enzyme such as enalapril, and one or more combined inhibitors of angiotensin-converting enzyme and neutral endopeptidase such as omapatrilat; and/or
(37) one or more tricyclic antidepressants, e.g. amitriptiline; and/or
(38) one or more non-steroidal anti-inflammatory agents; and/or
(39) one or more angiotensin-converting enzyme (ACE) inhibitors, e.g. quinapril; and/or
(40) one or more anti-depressants (such as clomipramine and SSRls (such as paroxetine and sertaline).
wherein said combination can be in the form of co-administration, simultaneous administration, concurrent administration, or stepwise administration.
The compounds of the invention are useful because they possess pharmacological activity in animals, especially mammals, including humans. They are therefore indicated as pharmaceuticals, as well as for use as animal medicaments.
In particular, compounds of the invention have been found to be potent and selective inhibitors of cGMP PDE5, for example as demonstrated in the tests described below, and are thus useful in the treatment of medical conditions in humans and other animals, in which cGMP PDE5 is indicated, and in which inhibition of cGMP PDE5 is desirable.
By the term xe2x80x9ctreatmentxe2x80x9d, we include both therapeutic (curative), palliative or prophylactic treatment.
Thus, according to a further aspect of the invention there is provided the use of the compounds of the invention in the manufacture of a medicament for the treatment of a medical condition in which cGMP PDE5 is indicated. There is further provided the use of the compounds of the invention in the manufacture of a medicament for the treatment of a medical condition in which inhibition of cGMP PDE5 is desirable.
The compounds of the invention are expected to be useful for the curative, palliative or prophylactic treatment of mammalian sexual disorders or any of the other conditions or disorders detailed hereinbefore. In particular, the compounds are of value in the treatment of mammalian sexual dysfunctions such as male erectile dysfunction (MED), impotence, female sexual dysfunction (FSD), clitoral dysfunction, female hypoactive sexual desire disorder, female sexual arousal disorder, female sexual pain disorder or female sexual orgasmic dysfunction (FSOD) as well as sexual dysfunction due to spinal cord injury or selective serotonin re-uptake inhibitor (SSRI) induced sexual dysfunction but, clearly, will be useful also for treating other medical conditions for which a potent and selective cGMP PDE5 inhibitor is indicated. Such conditions include premature labour, dysmenorrhoea, benign prostatic hyperplasia (BPH), bladder outlet obstruction, incontinence, stable, unstable and variant (Prinzmetal) angina, hypertension, pulmonary hypertension, chronic obstructive pulmonary disease, coronary artery disease, congestive heart failure, atherosclerosis, conditions of reduced blood vessel patency, e.g. post-percutaneous transluminal coronary angioplasty (post-PTCA), peripheral vascular disease, stroke, nitrate induced tolerance, bronchitis, allergic asthma, chronic asthma, allergic rhinitis, diseases and conditions of the eye such as glaucoma, optic neuropathy, macular degeneration, elevated intra-occular pressure, retinal or arterial occulsion and diseases characterised by disorders of gut motility, e.g. irritable bowel syndrome (IBS).
Further medical conditions for which a potent and selective cGMP PDE5 inhibitor is indicated, and for which treatment with compounds of the present invention may be useful include pre-eclampsia, Kawasaki""s syndrome, nitrate tolerance, multiple sclerosis, diabetic nephropathy, peripheral diabetic neuropathy, Alzheimer""s disease, acute respiratory failure, psoriasis, skin necrosis, cancer, metastasis, baldness, nutcracker oesophagus, diabetes mellitus, the insulin resistance syndrome, anal fissure, haemorrhoids, hypoxic vasoconstriction as well as the stabilisation of blood pressure during haemodialysis.
Particularly preferred conditions include MED and FSD.
Thus, the invention provides a method of treating or preventing a medical condition for which a cGMP PDE5 inhibitor is indicated, in an animal (e.g. a mammal, including a human being), which comprises administering a therapeutically effective amount of a compound of the invention to an animal in need of such treatment.
The compounds of the invention will normally be administered orally or by any parenteral route, in the form of pharmaceutical preparations comprising the active ingredient, optionally in the form of a non-toxic organic, or inorganic, acid, or base, addition salt, in a pharmaceutically acceptable dosage form. Depending upon the disorder and patient to be treated, as well as the route of administration, the compositions may be administered at varying doses.
The compounds of the invention may also be combined with any other drugs useful in the inhibition of cGMP-PDEs, such as cGMP-PDE5.
The compounds of the invention, their pharmaceutically acceptable salts, and pharmaceutically acceptable solvates of either entity can be administered alone but, in human therapy will generally be administered in admixture with a suitable pharmaceutical excipient diluent or carrier selected with regard to the intended route of administration and standard pharmaceutical practice.
For example, the compounds of the invention or salts or solvates thereof can be administered orally, buccally or sublingually in the form of tablets, capsules (including soft gel capsules), ovules, elixirs, solutions or suspensions, which may contain flavouring or colouring agents, for immediate-, delayed-, controlled-release such as modified-, dual-, sustained-, or pulsatile delivery applications. The compounds of the invention may also be administered via intracavernosal injection. The compounds of the invention may also be administered via fast dispersing or fast dissolving dosages forms.
Such tablets may contain excipients such as microcrystalline cellulose, lactose, sodium citrate, calcium carbonate, dibasic calcium phosphate, glycine and starch (preferably corn, potato or tapioca starch), disintegrants such as sodium starch glycollate, croscarmellose sodium and certain complex silicates, and granulation binders such as polyvinylpyrrolidone, hydroxypropylmethyl cellulose (HPMC), hydroxypropylcellulose (HPC), sucrose, gelatin and acacia. Additionally, lubricating agents such as magnesium stearate, stearic acid, glyceryl behenate and talc may be included.
Solid compositions of a similar type may also be employed as fillers in gelatin capsules. Preferred excipients in this regard include lactose, starch, a cellulose, milk sugar or high molecular weight polyethylene glycols. For aqueous suspensions and/or elixirs, the compounds of the invention may be combined with various sweetening or flavouring agents, colouring matter or dyes, with emulsifying and/or suspending agents and with diluents such as water, ethanol, propylene glycol and glycerin, and combinations thereof.
Modified release and pulsatile release dosage forms may contain excipients such as those detailed for immediate release dosage forms together with additional excipients that act as release rate modifiers, these being coated on and/or included in the body of the device. Release rate modifiers include, but are not exclusively limited to, hydroxypropylmethyl cellulose, methyl cellulose, sodium carboxymethylcellulose, ethyl cellulose, cellulose acetate, polyethylene oxide, Xanthan gum, Carbomer, ammonio methacrylate copolymer, hydrogenated castor oil, carnauba wax, paraffin wax, cellulose acetate phthalate, hydroxypropylmethyl cellulose phthalate, methacrylic acid copolymer and mixtures thereof. Modified release and pulsatile release dosage forms may contain one or a combination of release rate modifying excipients. Release rate modifying excipients maybe present both within the dosage form i.e. within the matrix, and/or on the dosage form i.e. upon the surface or coating.
Fast dispersing or dissolving dosage formulations (FDDFs) may contain the following ingredients: aspartame, acesulfame potassium, citric acid, croscarmellose sodium, crospovidone, diascorbic acid, ethyl acrylate, ethyl cellulose, gelatin, hydroxypropylmethyl cellulose, magnesium stearate, mannitol, methyl methacrylate, mint flavouring, polyethylene glycol, fumed silica, silicon dioxide, sodium starch glycolate, sodium stearyl fumarate, sorbitol, xylitol. The terms dispersing or dissolving as used herein to describe FDDFs are dependent upon the solubility of the drug substance used i.e. where the drug substance is insoluble a fast dispersing dosage form can be prepared and where the drug substance is soluble a fast dissolving dosage form can be prepared.
The compounds of the invention can also be administered parenterally, for example, intracavernosally, intravenously, intra-arterially, intraperitoneally, intrathecally, intraventricularly, intraurethrally intrasternally, intracranially, intramuscularly or subcutaneously, or they may be administered by infusion techniques. For such parenteral administration they are best used in the form of a sterile aqueous solution which may contain other substances, for example, enough salts or glucose to make the solution isotonic with blood.
The aqueous solutions should be suitably buffered (preferably to a pH of from 3 to 9), if necessary. The preparation of suitable parenteral formulations under sterile conditions is readily accomplished by standard pharmaceutical techniques well-known to those skilled in the art.
For oral and parenteral administration to human patients, the daily dosage level of the compounds of the invention or salts or solvates thereof will usually be from 10 to 500 mg (in single or divided doses).
Thus, for example, tablets or capsules of the compounds of the invention or salts or solvates thereof may contain from 5 mg to 250 mg of active compound for administration singly or two or more at a time, as appropriate. The physician in any event will determine the actual dosage which will be most suitable for any individual patient and it will vary with the age, weight and response of the particular patient. The above dosages are exemplary of the average case. There can, of course, be individual instances where higher or lower dosage ranges are merited and such are within the scope of this invention. The skilled person will also appreciate that, in the treatment of certain conditions (including MED and FSD), compounds of the invention may be taken as a single dose on an xe2x80x9cas requiredxe2x80x9d basis (i.e. as needed or desired).
In general a tablet formulation could typically contain between about 0.01 mg and 500 mg of a compound according to the present invention (or a salt thereof) whilst tablet fill weights may range from 50 mg to 1000 mg. An example formulation for a 10 mg tablet is illustrated:
Such tablets can be manufactured by standard processes, for example, direct compression or a wet or dry granulation process. The tablet cores may be coated with appropriate overcoats.
The compounds of the invention can also be administered intranasally or by inhalation and are conveniently delivered in the form of a dry powder inhaler or an aerosol spray presentation from a pressurised container, pump, spray or nebuliser with the use of a suitable propellant, e.g. dichlorodifluoromethane, trichlorofluoromethane, dichlorotetrafluoroethane, a hydrofluoroalkane such as 1,1,1,2-tetrafluoroethane (HFA 134A [trade mark] or 1,1,1,2,3,3,3-heptafluoropropane (HFA 227EA [trade mark]), carbon dioxide or other suitable gas. In the case of a pressurised aerosol, the dosage unit may be determined by providing a valve to deliver a metered amount. The pressurised container, pump, spray or nebuliser may contain a solution or suspension of the active compound, e.g. using a mixture of ethanol and the propellant as the solvent, which may additionally contain a lubricant, e.g. sorbitan trioleate. Capsules and cartridges (made, for example, from gelatin) for use in an inhaler or insufflator may be formulated to contain a powder mix of a compound of the invention and a suitable powder base such as lactose or starch.
Aerosol or dry powder formulations are preferably arranged so that each metered dose or xe2x80x9cpuffxe2x80x9d contains from 1 to 50 mg of a compound of the invention for delivery to the patient. The overall daily dose with an aerosol will be in the range of from 1 to 50 mg which may be administered in a single dose or, more usually, in divided doses throughout the day.
The compounds of the invention may also be formulated for delivery via an atomiser. Formulations for atomiser devices may contain the following ingredients as solubilisers, emulsifiers or suspending agents: water, ethanol, glycerol, propylene glycol, low molecular weight polyethylene glycols, sodium chloride, fluorocarbons, polyethylene glycol ethers, sorbitan trioleate, oleic acid.
Alternatively, the compounds of the invention or salts or solvates thereof can be administered in the form of a suppository or pessary, or they may be applied topically in the form of a gel, hydrogel, lotion, solution, cream, ointment or dusting powder. The compounds of the invention or salts or solvates thereof may also be dermally administered. The compounds of the invention or salts or solvates thereof may also be transdermally administered, for example, by the use of a skin patch. They may also be administered by the ocular, pulmonary or rectal routes.
For ophthalmic use, the compounds can be formulated as micronised suspensions in isotonic, pH adjusted, sterile saline, or, preferably, as solutions in isotonic, pH adjusted, sterile saline, optionally in combination with a preservative such as a benzylalkonium chloride. Alternatively, they may be formulated in an ointment such as petrolatum.
For application topically to the skin, the compounds of the invention or salts or solvates thereof can be formulated as a suitable ointment containing the active compound suspended or dissolved in, for example, a mixture with one or more of the following: mineral oil, liquid petrolatum, white petrolatum, propylene glycol, polyoxyethylene polyoxypropylene compound, emulsifying wax and water. Alternatively, they can be formulated as a suitable lotion or cream, suspended or dissolved in, for example, a mixture of one or more of the following: mineral oil, sorbitan monostearate, a polyethylene glycol, liquid paraffin, polysorbate 60, cetyl esters wax, cetearyl alcohol, 2-octyldodecanol, benzyl alcohol and water.
The compounds of the invention may also be used in combination with a cyclodextrin. Cyclodextrins are known to form inclusion and non-inclusion complexes with drug molecules. Formation of a drug-cyclodextrin complex may modify the solubility, dissolution rate, bioavailability and/or stability property of a drug molecule. Drug-cyclodextrin complexes are generally useful for most dosage forms and administration routes. As an alternative to direct complexation with the drug the cyclodextrin may be used as an auxiliary additive, e.g. as a carrier, diluent or solubiliser. Alpha-, beta- and gamma-cyclodextrins are most commonly used and suitable examples are described in WO-A-91/11172, WO-A-94/02518 and WO-A-98/55148.
Generally, in humans, oral administration of the compounds of the invention is the preferred route, being the most convenient and, for example in MED, avoiding the well-known disadvantages associated with intracavernosal (i.c.) administration. A preferred oral dosing regimen in MED for a typical man is from 25 to 250 mg of compound when required. In circumstances where the recipient suffers from a swallowing disorder or from impairment of drug absorption after oral administration, the drug may be administered parenterally, sublingually or buccally.
For veterinary use, a compound of the invention, or a veterinarily acceptable salt thereof, or a veterinarily acceptable solvate or pro-drug thereof, is administered as a suitably acceptable formulation in accordance with normal veterinary practice and the veterinary surgeon will determine the dosing regimen and route of administration which will be most appropriate for a particular animal.
Thus, according to a further aspect of the invention there is provided a pharmaceutical formulation including a compound of the invention in admixture with a pharmaceutically or veterinarily acceptable adjuvant, diluent or carrier.
In addition to the fact that compounds of the invention inhibit cyclic guanosine 3xe2x80x2,5xe2x80x2-monophosphate phosphodiesterases (cGMP PDEs) and in particular, are potent and selective inhibitors of cGMP PDE5, compounds of the invention may also have the advantage that they may be more efficacious than, be less toxic than, have a broader range of activity than, be more potent than, produce fewer side effects than, be more easily absorbed than, or they may have other useful pharmacological properties over, compounds known in the prior art.
Preferably the compounds of the invention are orally bioavailable. Oral bioavailablity refers to the proportion of an orally administered drug that reaches the systemic circulation. The factors that determine oral bioavailability of a drug are dissolution, membrane permeability and metabolic stability. Typically, a screening cascade of firstly in vitro and then in vivo techniques is used to determine oral bioavailablity.
Dissolution, the solubilisation of the drug by the aqueous contents of the gastro-intestinal tract (GIT), can be predicted from in vitro solubility experiments conducted at appropriate pH to mimic the GIT. Preferably the compounds of the invention have a minimum solubility of 50 mcg/ml. Solubility can be determined by standard procedures known in the art such as described in Adv. Drug Deliv. Rev. 23, 3-25, 1997.
Membrane permeability refers to the passage of the compound through the cells of the GIT. Lipophilicity is a key property in predicting this and is defined by in vitro Log D7.4 measurements using organic solvents and buffer. Preferably the compounds of the invention have a Log D7.4 of xe2x88x922 to +4, more preferably xe2x88x921 to +2. The log D can be determined by standard procedures known in the art such as described in J. Pharm. Pharmacol. 1990, 42:144.
Cell monolayer assays such as caco-2 add substantially to prediction of favourable membrane permeability in the presence of efflux transporters such as p-glycoprotein, so-called caco-2 flux. Preferably, compounds of the invention have a caco-2 flux of greater than 2xc3x9710xe2x88x926 cmsxe2x88x921, more preferably greater than 5xc3x9710xe2x88x926 cmsxe2x88x921. The caco flux value can be determined by standard procedures known in the art such as described in J. Pharm. Sci, 1990, 79, 595-600
Metabolic stability addresses the ability of the GIT or the liver to metabolise compounds during the absorption process: the first pass effect. Assay systems such as microsomes, hepatocytes etc. are predictive of metabolic liability. Preferably the compounds of the Examples show metabolic stablity in the assay system that is commensurate with an hepatic extraction of less then 0.5. Examples of assay systems and data manipulation are described in Curr. Opin. Drug Disc. Devel., 201, 4, 36-44, Drug Met. Disp., 2000, 28, 1518-1523
Because of the interplay of the above processes further support that a drug will be orally bioavailable in humans can be gained by in vivo experiments in animals. Absolute bioavailability is determined in these studies by administering the compound separately or in mixtures by the oral route. For absolute determinations (% absorbed) the intravenous route is also employed. Examples of the assessment of oral bioavailability in animals can be found in Drug Met. Disp., 2001, 29, 82-87; J. Med Chem, 1997, 40, 827-829, Drug Met. Disp., 1999, 27, 221-226
The biological activities of the compounds of the present invention were determined by the following test methods.
The compounds of the present invention are potent and selective cGMP PDE5 inhibitors. In vitro PDE inhibitory activities against cyclic guanosine 3xe2x80x2,5xe2x80x2-monophosphate (cGMP) and cyclic adenosine 3xe2x80x2,5xe2x80x2-monophosphate (cAMP) phosphodiesterases were determined by measurement of their IC50 values (the concentration of compound required for 50% inhibition of enzyme activity).
The required PDE enzymes were isolated from a variety of sources, including human corpus cavernosum, human platelets, human cardiac ventricle, human skeletal muscle and human and canine retina, essentially by the method of W. J. Thompson and M. M. Appleman (Biochem., 1971, 10, 311). In particular, the cGMP-specific PDE (PDE5) and the cGMP-inhibited cAMP PDE (PDE3) were obtained from human corpus cavernosum tissue or human platelets; the cGMP-stimulated PDE (PDE2) was obtained from human corpus cavernosum or human platelets; the calcium/calmodulin (Ca/CAM)-dependent PDE (PDE1) from human cardiac ventricle; the cAMP-specific PDE (PDE4) from recombinant clone or human skeletal muscle; and the photoreceptor PDE (PDE6) from canine or human retina. Phosphodiesterases 7-11 were generated from full length human recombinant clones transfected into SF9 cells.
Assays were performed either using a modification of the xe2x80x9cbatchxe2x80x9d method of W. J. Thompson et al. (Biochem., 1979, 18, 5228) or using a scintillation proximity assay for the direct detection of AMP/GMP using a modification of the protocol described by Amersham pic under product code TRKQ7090/7100. In summary, the effect of PDE inhibitors was investigated by assaying a fixed amount of enzyme in the presence of varying inhibitor concentrations and low substrate, (cGMP or cAMP in a 3:1 ratio unlabelled to [3H]-labeled at a conc xcx9cxc2xd Km) such that IC50 ≅Ki. The final assay volume was made up to 102 xcexcl with assay buffer [20 mM Tris-HCl pH 7.4, 5 mM MgCl2, 1 mg/ml bovine serum albumin]. Reactions were initiated with enzyme, incubated for 30-60 min at 30xc2x0 C. to give  less than 30% substrate turnover and terminated with 50 xcexcl yttrium silicate SPA beads (containing 3 mM of the respective unlabelled cyclic nucleotide for PDEs 3, 9 and 11). Plates were resealed and shaken for 20 min, after which the beads were allowed to settle for 30 min in the dark and then counted on a TopCount plate reader (Packard, Meriden, Conn.). Radioactivity units were converted to % activity of an uninhibited control (100%), plotted against inhibitor concentration and inhibitor IC50 values obtained using the xe2x80x98Fit Curvexe2x80x99 Microsoft Excel extension or inhouse equivalent. Results from these tests show that the compounds of the present invention are potent and selective inhibitors of cGMP-specific PDE5.
This can be assessed in vitro by determining the capacity of a compound of the invention to enhance sodium nitroprusside-induced relaxation of pre-contracted rabbit corpus cavernosum tissue strips, as described by S. A. Ballard et al. (Brit. J. Pharmacol., 1996, 118 (suppl.), abstract 153P).
This can be assessed by screening the compounds of the invention in anaesthetised dogs to determine their capacity, after i.v. administration, to enhance the pressure rises in the corpora cavernosa of the penis induced by intracavernosal injection of sodium nitroprusside, using a method based on that described by Trigo-Rocha et al. (Neurourol. and Urodyn., 1994, 13, 71).
Compounds of the invention can be tested at varying i.v and p.o. doses in animals such as mouse and dog, observing for any untoward effects.
In vitro metabolism experiments were carried out in the hepatic microsomal fractions from man. Transplant-quality human liver tissue was obtained from the International Institute for the Advancement of Medicine (Exton, Pa., USA). Microsomes were prepared according to the method described in Biochemical Pharmacology, 1966, 48, 2147-2156 and stored at xe2x88x9280xc2x0 C. The concentrations of protein and cytochrome P450 were determined by standard methods described in Journal of Biological Chemistry, 1951, 193, 265-275 and Journal of Biological Chemistry, 1964, 239, 2370-2378.
Microsomal incubations (1.5 ml) were prepared containing 0.5 xcexcM cytochrome P450, 200 mM phosphate buffer (pH 7.4), 0.1 M MgCl2, 0.1 M isocitric acid, 1 unit/ml isocitrate dehydrogenase and 20 mM xcex2-NADP. Compounds under study were added after a 5 min preincubation at 37xc2x0 C. to give an initial substrate concentration of 1 xcexcM. The mixture was incubated at 37xc2x0 C. and samples (100 xcexcl) were removed for analysis for up to 60 min. Metabolism in samples was terminated by the addition of NaOH (0.1 M) containing an internal standard (chosen to have similar physicochemical properties to compounds under study), followed by extraction into ethyl acetate (2 ml). The extracts were evaporated to dryness and analysed by LC-MS/MS (Hewlett Packard HP1100 binary pump, Hypersil HS100 C18, 5 cm by 4.6 mm internal diameter, 5 xcexcm column using a mobile phase of 2 mM ammonium acetate in 90:10 methanol/water, aqueous portion adjusted to pH 4 with glacial acetic acid, and a flowrate of 1 ml/min). The mass spectrometer was a Sciex API 2000 with TurbolonSpray interface using a positive ion multiple reaction monitoring (MRM) detection mode. Nitrogen was used as curtain, nebuliser, TurbolonSpray and collision gases, and the TurbolonSpray temperature was 100xc2x0 C. Typical voltages were as follows: IS=5.2 kV; RNG=380 V; Q0=xe2x88x9210 V; IQ1=xe2x88x9211 V; ST=xe2x88x9215;RO1=xe2x88x9211 V; MU=gain adjusted as per Sciex user manual. Collision energy was 55 eV for high MRM, OR=65 V. Dwell time was 200 msec with a 50 msec pause. Data was acquired using MSExpress v 1.1 and processed using Macquan 1.5 (PE Sciex)). Disappearance rate constants (k) in human microsomal preparations were determined by linear regression of the log ratio (compound under study/internal standard) versus time. The in vitro human microsomal half-lives were determined according to the equation t{fraction (1/12)}=In 2/k. Results from these studies show that the compounds of the present invention have human liver microsome (HLM) half-lives greater than the HLM half-lives of known compounds of the art.
Thus a particular advantage of the compounds of the invention is that they have longer in vitro microsomal half-lives than compounds of the art. Such improved in vitro microsomal half-lives are indicative of reduced clearance in vivo.
Preferred compounds of the present invention, such as those of Examples 1-22, 24-26 and 28-29 have IC50 values of less than about 30 nM for the PDE5 enzyme. More preferred compounds, such as those of Examples 1-3,5,7-19, 24-25 and 28-29 have IC50 values of less than about 10 nM for the PDE5 enzyme.
Especially preferred herein are compounds which have an IC50 value of less than about 30 nM, and more preferably less than 10 nM for the PDE5 enzyme and especially less than 5 nM for the PDE5 enzyme in combination with selectivity of greater than 10-fold, more preferably greater than 50-fold, more preferably greater than 100-fold and most preferably greater than 200-fold selectivity for the PDE5 enzyme versus the PDE6 enzyme.
An especially preferred subset of the compounds described in the previous paragraph are compounds with human liver microsome (HLM) half-lives greater than about 30 minutes, more preferably greater than 60 minutes, and most preferably greater than 120 minutesxe2x80x94when measured according to the methods detailed hereinbefore. Preferred compounds herein having HLM half-lifes greater than or equal to about 30 minutes include the compounds of examples 1, 2, 9, 11, 12, 14, 18 and 19.
Those skilled in the art will recognise that an increase in HLM half-life is predictive of reduced clearance in man for compounds cleared predominantly by cytochrome P450 mediated metabolism.